已知sin(a+b)=1/2 sin(a-b)=1/10 求sinacosb cosasinb
5个回答

sin(a+b)=sinacosb+cosasinb=1/2

sin(a-b)=sinacosb-cosasinb=1/10 联立解得sinacosb=3/10 cosasinb=1/5

sinacosb/cosasinb=(sina/cosa)/(sinb/cosb)=3/2

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